#ifndef __DLIST_H  
#define __DLIST_H  

/* This file is from Linux Kernel (include/linux/list.h) 
 * and modified by simply removing hardware prefetching of list items. 
 * Here by copyright, credits attributed to wherever they belong. 
 * Kulesh Shanmugasundaram (kulesh [squiggly] isis.poly.edu) 
 */  

/* 
 * Simple doubly linked list implementation. 
 * 
 * Some of the internal functions (“__xxx”) are useful when 
 * manipulating whole lists rather than single entries, as 
 * sometimes we already know the next/prev entries and we can 
 * generate better code by using them directly rather than 
 * using the generic single-entry routines. 
 */  
/** 
 * container_of - cast a member of a structure out to the containing structure 
 * 
 * @ptr:    the pointer to the member. 
 * @type:   the type of the container struct this is embedded in. 
 * @member: the name of the member within the struct. 
 *typeof(type)是gcc的扩展，是得到type的数据类型，和我们比较熟悉的sizeof()比较类似。 
 */
#ifndef offsetof
#define offsetof(TYPE, MEMBER) ((size_t) &((TYPE *)0)->MEMBER)  
#endif

#ifndef container_of
#define container_of(ptr, type, member) ({ \
        const typeof( ((type *)0)->member ) *__mptr = (ptr); \
        (type *)( (char *)__mptr - offsetof(type,member) );})  
#endif
/* 
 * These are non-NULL pointers that will result in page faults 
 * under normal circumstances, used to verify that nobody uses 
 * non-initialized list entries. 
 */  
#define LIST_POISON1  ((void *) 0x00100100)  
#define LIST_POISON2  ((void *) 0x00200)  

struct list_head {  
    struct list_head *next, *prev;  
};  

#define LIST_HEAD_INIT(name) { &(name), &(name) }  

#define LIST_HEAD(name) \
    struct list_head name = LIST_HEAD_INIT(name)  

#define INIT_LIST_HEAD(ptr) do { \
    (ptr)->next = (ptr); (ptr)->prev = (ptr); \
} while (0)  

    /* 
     * Insert a new entry between two known consecutive entries. 
     * 
     * This is only for internal list manipulation where we know 
     * the prev/next entries already! 
     */  
static inline void __list_add(struct list_head *new,  
        struct list_head *prev,  
        struct list_head *next)  
{  
    next->prev = new;  
    new->next = next;  
    new->prev = prev;  
    prev->next = new;  
}  

/** 
 * list_add – add a new entry 
 * @new: new entry to be added 
 * @head: list head to add it after 
 * 
 * Insert a new entry after the specified head. 
 * This is good for implementing stacks. 
 */  
static inline void list_add(struct list_head *new, struct list_head *head)  
{  
    __list_add(new, head, head->next);  
}  

/** 
 * list_add_tail – add a new entry 
 * @new: new entry to be added 
 * @head: list head to add it before 
 * 
 * Insert a new entry before the specified head. 
 * This is useful for implementing queues. 
 */  
static inline void list_add_tail(struct list_head *new, struct list_head *head)  
{  
    __list_add(new, head->prev, head);  
}  

/* 
 * Delete a list entry by making the prev/next entries 
 * point to each other. 
 * 
 * This is only for internal list manipulation where we know 
 * the prev/next entries already! 
 */  
static inline void __list_del(struct list_head *prev, struct list_head *next)  
{  
    next->prev = prev;  
    prev->next = next;  
}  

/** 
 * list_del – deletes entry from list. 
 * @entry: the element to delete from the list. 
 * Note: list_empty on entry does not return true after this, the entry is in an undefined state. 
 */  
static inline void list_del(struct list_head *entry)  
{  
    __list_del(entry->prev, entry->next);  
    entry->next = (void *) 0;  
    entry->prev = (void *) 0;  
}  


/** 
 * list_del_init – deletes entry from list and reinitialize it. 
 * @entry: the element to delete from the list. 
 */  
static inline void list_del_init(struct list_head *entry)  
{  
    __list_del(entry->prev, entry->next);  
    INIT_LIST_HEAD(entry);  
}  

/** 
 * list_move – delete from one list and add as another’s head 
 * @list: the entry to move 
 * @head: the head that will precede our entry 
 */  
static inline void list_move(struct list_head *list,  
        struct list_head *head)  
{  
    __list_del(list->prev, list->next);  
    list_add(list, head);  
}  

/** 
 * list_move_tail – delete from one list and add as another’s tail 
 * @list: the entry to move 
 * @head: the head that will follow our entry 
 */  
static inline void list_move_tail(struct list_head *list,  
        struct list_head *head)  
{  
    __list_del(list->prev, list->next);  
    list_add_tail(list, head);  
}  

/** 
 * list_empty – tests whether a list is empty 
 * @head: the list to test. 
 */  
static inline int list_empty(struct list_head *head)  
{  
    return head->next == head;  
}  

static inline void __list_splice(struct list_head *list,  
        struct list_head *head)  
{  
    struct list_head *first = list->next;  
    struct list_head *last = list->prev;  
    struct list_head *at = head->next;  

    first->prev = head;  
    head->next = first;  

    last->next = at;  
    at->prev = last;  
}  

/** 
 * list_splice – join two lists 
 * @list: the new list to add. 
 * @head: the place to add it in the first list. 
 */  
static inline void list_splice(struct list_head *list, struct list_head *head)  
{  
    if (!list_empty(list))  
        __list_splice(list, head);  
}  

/** 
 * list_splice_init – join two lists and reinitialise the emptied list. 
 * @list: the new list to add. 
 * @head: the place to add it in the first list. 
 * 
 * The list at @list is reinitialised 
 */  
static inline void list_splice_init(struct list_head *list,  
        struct list_head *head)  
{  
    if (!list_empty(list)) {  
        __list_splice(list, head);  
        INIT_LIST_HEAD(list);  
    }  
}  

/** 
 * list_entry – get the struct for this entry 
 * @ptr:    the &struct list_head pointer. 
 * @type:    the type of the struct this is embedded in. 
 * @member:    the name of the list_struct within the struct. 
 */  
#define list_entry(ptr, type, member) \
    ((type *)((char *)(ptr)-(unsigned long)(&((type *)0)->member)))  

/** 
 * list_for_each    -    iterate over a list 
 * @pos:    the &struct list_head to use as a loop counter. 
 * @head:    the head for your list. 
 */  
#define list_for_each(pos, head) \
    for (pos = (head)->next; pos != (head); \
            pos = pos->next)  
/** 
 * list_for_each_prev    -    iterate over a list backwards 
 * @pos:    the &struct list_head to use as a loop counter. 
 * @head:    the head for your list. 
 */  
#define list_for_each_prev(pos, head) \
    for (pos = (head)->prev; pos != (head); \
            pos = pos->prev)  

/** 
 * list_for_each_safe    -    iterate over a list safe against removal of list entry 
 * @pos:    the &struct list_head to use as a loop counter. 
 * @n:        another &struct list_head to use as temporary storage 
 * @head:    the head for your list. 
 */  
#define list_for_each_safe(pos, n, head) \
    for (pos = (head)->next, n = pos->next; pos != (head); \
            pos = n, n = pos->next)  

/** 
 * list_for_each_entry    -    iterate over list of given type 
 * @pos:    the type * to use as a loop counter. 
 * @head:    the head for your list. 
 * @member:    the name of the list_struct within the struct. 
 */  
#define list_for_each_entry(pos, head, member)                \
    for (pos = list_entry((head)->next, typeof(*pos), member);    \
            &pos->member != (head);                     \
            pos = list_entry(pos->member.next, typeof(*pos), member))

/** 
 * list_for_each_entry_safe – iterate over list of given type safe against removal of list entry 
 * @pos:    the type * to use as a loop counter. 
 * @n:        another type * to use as temporary storage 
 * @head:    the head for your list. 
 * @member:    the name of the list_struct within the struct. 
 */  
#define list_for_each_entry_safe(pos, n, head, member)            \
    for (pos = list_entry((head)->next, typeof(*pos), member),    \
            n = list_entry(pos->member.next, typeof(*pos), member);    \
            &pos->member != (head);                     \
            pos = n, n = list_entry(n->member.next, typeof(*n), member))  

static inline int list_count(struct list_head *head)
{
    int cnt = 0;
    struct list_head *pos;
    list_for_each(pos, head) {
        cnt++;
    }
    return cnt;
}

static inline int list_have(struct list_head *head, struct list_head *new)
{
    struct list_head *pos;
    list_for_each(pos, head) {
        if(pos == new) return 1;
    }
    return 0;
}

#endif  
